The ultimate objective of the proposed study is to test the effectiveness, implementation quality, and cost effectiveness of family-based treatment services for adolescent substance abuse delivered in an agency setting. Despite the success of family-based ecological interventions (FBEI) in controlled trials, this highly promising services approach has not been tested under pure field conditions with ASA populations. Controlled effectiveness research invariably enhances training, supervision, and service delivery conditions in partnering sites in an effort to ensure treatment adherence and consistency. An alternative strategy for advancing dissemination science is rigorous naturalistic research on community clinics that already implement evidence-based practices in the course of routine care. The proposed study will follow this "bottom up" strategy by investigating the quality and impact of ASA services delivered by front-line therapists in a community-based mental health center that already features FBEI as the routine standard of care. The study will use a randomized design to compare naturalistic FBEI services to services as usual (SAD) for ASA. Participants (N = 260)will be recruited from local high schools, enrichment programs, and juvenile justice programs. Eligible adolescents will meet ASAM criteria for outpatient treatment. The SAD condition will contain the three most common service venues for ASA in urban communities: hospital-based ambulatory mental health clinics, drug counseling/addictions specialty clinics, and community mental health centers. The primary aims of the study are to examine the effectiveness of FBEI versus SAD and to compare the strength of FBEI adherence and outcomes to performance benchmarks set during a previous FBEI Stage II efficacy trial. The secondary aims are to compare cost effectiveness, services utilization, and consumer satisfaction in FBEI versus SAU. A multitrait, multimethod assessment design will include adolescent and parent interviews at baseline and 3, 6, and 12 months follow-up. Cost and service utilization data will be collected from self report and from provider agencies in both conditions. The study will yield the first evidence on whether a widely endorsed treatment approach for ASA is potent and feasible in real-world conditions and superior to SAU in outcomes and cost-benefit. An important secondary yield will be increasing the scarce knowledge base on commonly practiced community approaches in the SAU condition.